Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Wont rev past 6k and brown oil

Reply to topic
Bike Chat Forums Index -> The Workshop Goto page 1, 2  Next
View previous topic : View next topic  
Author Message

Ayrton
World Chat Champion



Joined: 02 Sep 2010
Karma :

PostPosted: 16:44 - 04 Mar 2019    Post subject: Wont rev past 6k and brown oil Reply with quote

Hi guys,
So i've been steadily working on my cbr125 project for about a year (other stuff took over) and it's gotten to the point where I thought everything was done and ready for the MOT.
Took it out this morning for a quick test run up the road and found that the engine just refuses to go past 6k revs and bogs down about there. After about 2 minutes ride I stopped to inspect it and the bike cut out. It became pretty reluctant to start and then after a few tries it jerked the bike foward as if the clutch was engaged (bike was in first gear with lever in). After a few tries it started and i steadily got it back home.

I read somewhere that old oil can cause a clutch to bind so I decided to drain the oil out (I stupidly never changed it) and found it to be a very light brown colour. Changed the oil and now once the bike is warmed up a little theres what I think is a lot of smoke coming out of the exhaust and the bike wont rev past 6k. Neither of these we're happening before the test run, but I didnt really run the bike a whole lot before that.

I've done some reading and people are saying theres likely coolant leaking into the oil to cause this?
I've done some basic maintenance like valve clearance and new spark plug, so I know thats good. One thing that may be a problem is that I changed the cylinder head a while back because the exhaust mount was knackered, so I wonder if I did something wrong there.

Does anyone have any ideas on what could be the problem?

Thanks for any help.
 Back to top
View user's profile Send private message You must be logged in to rate posts

mpd72
Formerly known as
mpd72 CPT



Joined: 22 Oct 2013
Karma :

PostPosted: 16:56 - 04 Mar 2019    Post subject: Reply with quote

How much oil came out and how much went back in?

Water in the oil will cause a milky colour. Is it losing coolant?
____________________
TZR250 2MA road, TZR250 1KT road, TZR250 2MA race, TDR250, YZF-750R Boost colours.
Jaguar S Type 3.0 V6 Sport R, VW Transporter T5 GP LWB Shuttle 140ps DSG.
 Back to top
View user's profile Send private message You must be logged in to rate posts

ThunderGuts
Scooby Slapper



Joined: 13 Nov 2018
Karma :

PostPosted: 17:06 - 04 Mar 2019    Post subject: Reply with quote

Is it smoke or steam? If your cooling system is knackered then coolant could be getting places it shouldn't causing steam.
____________________
Rob
 Back to top
View user's profile Send private message You must be logged in to rate posts

rpsmith79
Brolly Dolly



Joined: 31 Jan 2017
Karma :

PostPosted: 17:07 - 04 Mar 2019    Post subject: Reply with quote

Did you put on a fresh Head Gasket when you changed the cylinder head (or any head gasket at all??????)
____________________
Current Bike: Honda CG125 ES4 // Honda CB600FS Hornet
 Back to top
View user's profile Send private message You must be logged in to rate posts

Robby
Dirty Old Man



Joined: 16 May 2002
Karma :

PostPosted: 17:09 - 04 Mar 2019    Post subject: Reply with quote

My money is on a cylinder head cockup. Timing is out by a tooth, or you've cocked up the valve clearances and left them too tight.

Or the carb/throttle body doesn't have a good seal to the head. Not sure they connect up on the CBR125, but a pinched rubber or missing o-ring can give you an air leak.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Ayrton
World Chat Champion



Joined: 02 Sep 2010
Karma :

PostPosted: 18:07 - 04 Mar 2019    Post subject: Reply with quote

Thanks guys. I put 1l of oil in and theres room for a little more and about 1.25l came out, so it's not too bad. It's a very milky brown colour that looks the same as it does here https://www.youtube.com/watch?v=wBttgKH9ujA

I'm not sure if it's smoke or steam to be honest. It doesnt start doing it until the bike is decently warm if that matters.

I definitely changed the head gasket as I bought a whole set for the bike so I could do whatever I had to take off. There definetly is a chance I did something wrong so I will have a look inside and check that everything is as it should be.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :

PostPosted: 19:01 - 04 Mar 2019    Post subject: Reply with quote

Ayrton wrote:
Thanks guys. I put 1l of oil in and theres room for a little more and about 1.25l came out, so it's not too bad. It's a very milky brown colour that looks the same as it does here https://www.youtube.com/watch?v=wBttgKH9ujA


Eurgh. You should get the lid off and have a look, that oil has the lubricating properties of sewage sludge. Perhaps there's damage on the mating surfaces or something?
 Back to top
View user's profile Send private message You must be logged in to rate posts

Grubscrew
Nova Slayer



Joined: 23 Dec 2018
Karma :

PostPosted: 19:44 - 04 Mar 2019    Post subject: Reply with quote

Head to block seal. O ring missing/ damaged me thinks.
____________________
FJR1300/CB500x
 Back to top
View user's profile Send private message You must be logged in to rate posts

Robby
Dirty Old Man



Joined: 16 May 2002
Karma :

PostPosted: 23:49 - 04 Mar 2019    Post subject: Reply with quote

Could just be that you didn't get the mating surfaces clean enough.

You're asking some fairly basic questions, you admit to not doing oil changes very often, which suggest you're a muppet with a toolbox. Lots of things you can cock up doing a top-end rebuild on a 4 stroke.

So whilst I don't know what it is, I'll assume it's something you broke.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kentol750
Traffic Copper



Joined: 24 May 2016
Karma :

PostPosted: 23:55 - 04 Mar 2019    Post subject: Reply with quote

Pass the popcorn
____________________
Some bikes.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Ayrton
World Chat Champion



Joined: 02 Sep 2010
Karma :

PostPosted: 00:01 - 05 Mar 2019    Post subject: Reply with quote

Grubscrew wrote:
Head to block seal. O ring missing/ damaged me thinks.

There was only a metal crush type gasket between them I think and I definetly put a new one in, unless theres something else I'm missing?

Having a think about it though I dont think I ever torqued the camshaft holder nuts and head bolts down to anything specific as I didnt own any 1/4" sockets for my wrench at the time... The manual only gives a specification for the camshaft holder nuts which is 29nm. worth checking I think.
 Back to top
View user's profile Send private message You must be logged in to rate posts

steve the grease
Borekit Bruiser



Joined: 26 Jan 2018
Karma :

PostPosted: 00:32 - 05 Mar 2019    Post subject: Reply with quote

If the oil is the colour of chicken gravy, or caramac chocolate then it is definitely water in the oil. If you didn't tighten the head down to a preset torque , the there is your answer. I simply don't believe that there is not torque figure given for the cylinder head bolts. there is even a torque figure for a Morris thousand , so anything more modern has got to have a figure .... somewhere in the book
Get the head sorted , then redo the timing and you might have an answer to the 6k problem.
Just looked
Its 30 Nm or 22 ftlb
 Back to top
View user's profile Send private message You must be logged in to rate posts

Robby
Dirty Old Man



Joined: 16 May 2002
Karma :

PostPosted: 09:42 - 05 Mar 2019    Post subject: Reply with quote

Put your location in your profile and someone might come round and lend a hand.
 Back to top
View user's profile Send private message You must be logged in to rate posts

rpsmith79
Brolly Dolly



Joined: 31 Jan 2017
Karma :

PostPosted: 09:56 - 05 Mar 2019    Post subject: Reply with quote

Have you actually got documents for this bike yet, since you never actually replied in your original thread Wink
____________________
Current Bike: Honda CG125 ES4 // Honda CB600FS Hornet
 Back to top
View user's profile Send private message You must be logged in to rate posts

bikenut
World Chat Champion



Joined: 21 Nov 2011
Karma :

PostPosted: 10:54 - 05 Mar 2019    Post subject: bike Reply with quote

the video shows what looks just like emulsified oil, water in the oil.

You have a manual and know of cmsnl for the exploded views which can only help, they show you whats there, or should be there.

You did torque the head down didnt you?

how is the thermostate?

what year is the bike, you dont say.

https://images.cmsnl.com/img/partslists/honda-cbr125r-2004-4-england-cylinder-head_bigecpp4e1e__0200_14c2.gif

this is a link to a cbr125r, which may or may not be your exact bike, find your exact bike on cmsnl and have a look see.
____________________
nuts about bikes
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Ayrton
World Chat Champion



Joined: 02 Sep 2010
Karma :

PostPosted: 20:47 - 05 Mar 2019    Post subject: Reply with quote

Ok So I think I've just made things a lot worse Laughing
Took the head cover off and torqued the camshaft holder nuts down to 29Nm, turned out there was loads of room to go so I think that was the issue.
I then set about to do what the Haynes calls "cylinder head bolts" (no 12 on https://images.cmsnl.com/img/partslists/honda-cbr125r-2004-4-england-cylinder-head_bigecpp4e1e__0200_14c2.gif). Because I cant see any spec anywhere for these I set them to 30Nm like Steve said, except it must be a different bolt he's talking about as I just snapped the end right off one of them...
https://i.imgur.com/Ip4Tema.jpg

Also the bike is a 2010 model and I do have the documents now so I know it's not been nicked like everyone thought Laughing
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :

PostPosted: 21:41 - 05 Mar 2019    Post subject: Reply with quote

Now you'll have to take it to bits.... good chance to check things out.... that's a lot of stretch in the threads. Is it an 8mm bolt?

Edit: Hm. Bolt, Flange, 6x105 Cbr125r 2004 (4) England


http://www.wtools.com.tw/STANDARD-BOLT-TIGHTENING-TORQUE.shtml

(although IT DEPENDS on what you're bolting down/together/into).

Edit: Ooops now I see it's a 2010 one not 2004.


Last edited by Riejufixing on 00:11 - 06 Mar 2019; edited 1 time in total
 Back to top
View user's profile Send private message You must be logged in to rate posts

Robby
Dirty Old Man



Joined: 16 May 2002
Karma :

PostPosted: 23:52 - 05 Mar 2019    Post subject: Reply with quote

Oh my, this will be a fun thread. You just tried to put 30nm through what looks like an M5 bolt.

Just buy an engine, and get someone else to fit it. Whilst this will be excellent thread and you will be milked until dry, fixing this will cost you an awful lot of time and money.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :

PostPosted: 00:09 - 06 Mar 2019    Post subject: Reply with quote

Robby wrote:
Oh my, this will be a fun thread. You just tried to put 30nm through what looks like an M5 bolt.

Just buy an engine, and get someone else to fit it. Whilst this will be excellent thread and you will be milked until dry, fixing this will cost you an awful lot of time and money.


It seems to be M6 ISO coarse. Look at the mount of stretch in the remaining threaded portion The "new pitch" looks like about 1.5mm!!

I'd stick my neck out and say that the engine should be quite easy to salvage, if running it on mayonnaise for a few minutes hasn't shagged the mains. Even then.
 Back to top
View user's profile Send private message You must be logged in to rate posts

rpsmith79
Brolly Dolly



Joined: 31 Jan 2017
Karma :

PostPosted: 09:05 - 06 Mar 2019    Post subject: Reply with quote

Riejufixing wrote:
Robby wrote:
Oh my, this will be a fun thread. You just tried to put 30nm through what looks like an M5 bolt.

Just buy an engine, and get someone else to fit it. Whilst this will be excellent thread and you will be milked until dry, fixing this will cost you an awful lot of time and money.


It seems to be M6 ISO coarse. Look at the mount of stretch in the remaining threaded portion The "new pitch" looks like about 1.5mm!!

I'd stick my neck out and say that the engine should be quite easy to salvage, if running it on mayonnaise for a few minutes hasn't shagged the mains. Even then.


That bolt does look very odd, and i'm not sure how exactly you could stretch the thread to that extent, unless it was made of plasticine

Looks more like a self tapping thread than any machine screw i have ever seen

Even an M6 course thread has a pitch of 1.0mm, and i would suspect a head bolt would be fine pitch, which should make it 0.5mm, that look more like 2mm pitch

EDIT: Here is what it should look like, does actually look like a course thread

https://www.bikechatforums.com/download.php?id=102120
____________________
Current Bike: Honda CG125 ES4 // Honda CB600FS Hornet
 Back to top
View user's profile Send private message You must be logged in to rate posts

bikenut
World Chat Champion



Joined: 21 Nov 2011
Karma :

PostPosted: 11:39 - 06 Mar 2019    Post subject: bike Reply with quote

https://images.cmsnl.com/img/partslists/honda-cbr125rw-2010-a-englandbla-crankcase_big00028225e__1400_0b33.gif



Head studs?? Which will have nuts, domed ones probably, will be back in a moment, no not domed but they do have a washer, copper probably.


https://images.cmsnl.com/img/partslists/honda-cbr125rw-2010-a-englandbla-cylinder-head-cbr125rw7rw9rwa_big00028225e__0201_10ad.gif



you are gunna learn the hard way me thinks, first learn how to "read" the cmsnl exploded views, and the parts descriptions, then the manual, and then relate what you have learned to the bike so you don't break stuff!

Post a pic of the remains of the broken stud, the long bit and the bit that may be stuck in the engine part.

But first, find your exact bike on cmsnl and go from there, the views shown above in this thread may not be for your exact bike. FIND OUT!

https://images.cmsnl.com/img/partslists/honda-cbr125rw-2010-a-englandbla-cylinder_big00028225e__0500_2e2d.gif

At least you have a torque wrench, look up "average" torque values for 6 mm bolts, but for your particular bolt, find out the exact toque valve, don't just assume or guess.

Hows my spelling and grammer today dude, better than your mechanicing.....again sorry for the "attitude" we all had to start somewhere.......
____________________
nuts about bikes
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Ayrton
World Chat Champion



Joined: 02 Sep 2010
Karma :

PostPosted: 17:43 - 06 Mar 2019    Post subject: Re: bike Reply with quote

bikenut wrote:

Head studs?? Which will have nuts, domed ones probably, will be back in a moment, no not domed but they do have a washer, copper probably.

Not the studs, those are still ok. It's the m6x105 cylinder head bolts that I snapped (no 9 on your pic https://images.cmsnl.com/img/partslists/honda-cbr125rw-2010-a-englandbla-cylinder-head-cbr125rw7rw9rwa_big00028225e__0201_10ad.gif).
Having a look in the Honda manual theres no mention of a torque for these, just saying to alternate tightening them down. I'll find out from Honda to be sure.
https://www.manualslib.com/manual/1244336/Honda-Cbr125r.html?page=202#manual

The studs torqued down fine and I thought that the movement I was getting from these M6 bolts was just some free room that was created from tightening the head down more.
It's been streched a lot so thats whats making the pitch look massive. I'll see if I can get a side by side shot with the good bolt thats left.

I'm under no illusion that i'm an amazing mechanic and I get the "attitude", these are probably quite silly mistakes Laughing . I think your right about studying the manuals more and it would probably help if I didnt always rush things like this after work.

I will try and get some better pictures of what happened once I get home.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Ayrton
World Chat Champion



Joined: 02 Sep 2010
Karma :

PostPosted: 21:45 - 06 Mar 2019    Post subject: Reply with quote

So bit of a success tonight I think. Took the cylinder off to find the broken bolt just slightly sticking out of the hole. A little poking and it spun out quite nicely.
https://i.imgur.com/4YU4jM8.jpg
https://i.imgur.com/m5flfjA.jpg

Only thing that worries me is a lot of water came out of the engine when I pulled the cylinder head off. I think from the coolant passages.

Looking at the piston and cylinder I dont see any obvious damage.
https://i.imgur.com/km2Bof1.jpg

Do you guys think it's ok to put it back together with some fresh oil/ gaskets and see how it does?
 Back to top
View user's profile Send private message You must be logged in to rate posts

jaffa90
World Chat Champion



Joined: 06 Apr 2016
Karma :

PostPosted: 22:23 - 06 Mar 2019    Post subject: Reply with quote

I don`t like the look at that cyl wall, it should look polished.
Is it full of bits?
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :

PostPosted: 22:45 - 06 Mar 2019    Post subject: Reply with quote

Ayrton wrote:
Took the cylinder off to find the broken bolt just slightly sticking out of the hole. A little poking and it spun out quite nicely.


Good, good, thought it would...

Ayrton wrote:
Only thing that worries me is a lot of water came out of the engine when I pulled the cylinder head off. I think from the coolant passages.


Yes, that's most likely, I see droplets in the bore I think. Yes?

Ayrton wrote:
Looking at the piston and cylinder I dont see any obvious damage.

Do you guys think it's ok to put it back together with some fresh oil/ gaskets and see how it does?


Drain all the oil out, and attend to the filter, too. Make sure you have a new head gasket, and that the head/barrel faces are perfectly clean and undamaged, and that you replace the base gasket if need be. Put it back together and torque it up to I would guess 8nm[1], make sure you're timing's right, and finish putting it together and sticking oil & water in it. I still think that if you did not go very far/fast your main bearings might be OK. Time will tell.

1) Your indicated manual says (p16): "6 mm bolt and nut (Include SH flange bolt) 10nm"


Last edited by Riejufixing on 00:32 - 07 Mar 2019; edited 1 time in total
 Back to top
View user's profile Send private message You must be logged in to rate posts
Display posts from previous:   

Post new topic   Reply to topic    Bike Chat Forums Index -> The Workshop All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 

Debug Mode: ON - Server: discovery (www) - Page Generation Time: 0.40 Sec - Server Load: 3.84 - MySQL Queries: 16 - CDN Objects: 43 - Page Size: 138.25 Kb